Propeller



Nov. 10, 1931. l J. sQugREs 1,831,373

l PROPELLER Filed Dec. '20, k1928 A TORNEY gether by a special methodWherebyto insure,

Ijoined together by a Patented Nov. 10, 1931 UNITED STATES JOHN'SQUIRES, 0F DETROIT, MICHIGAN PROPELLER Application filed December 20,1928. Serial No. 327,227.

This invention relates to propellers and particularly to propellers ofthat type generally employed in connection with aircraft, the principalobject being the provision of a metallic propeller of novel constructionthat will be light in weight but of sufficiently great strength towithstand the stresses set up therein by the centrifugal forces at highro-` tational speeds, together with a method of making the same.

Another object is to provide a propeller blade fabricated in two halvesfrom a special alloy steel, the two halves being welded toa clean andperfect union between the two halves.

Another object is to provide a propeller which-outside of certain hubportions is made in two halves suitably shaped and integrally Weldingprocess.

Another object is to provide a metal propeller construction particularlydesigned to resist centrifugal forces at high rotational speeds, amarked stiifening being effected by asurface treatment.

Another object is, to provide a propeller that will be light in weight,of relatively great strength, impervious to rain or hail, relativelyresistant to the effect of bullets, and of relatively great life.

Another object is t'o provide a propeller blade formed of steel or analloy thereof and having the outer surface thereof case hardened.

A further object is to provide a method of forming a propeller bladewhich comprises forming said blade from non-hardened steel, carbonizing.the surface of the blade and then quenching the blade whereby to producea case hardened surface therefor.

e The above being among the objects 'of the present invention, the sameconsists in certain features of construction and combinations of part-sto be hereinafter described with reference to the accompanying drawings,and then claimed, having the above and other objects in view.

In t-he accompanying drawings which show a suitable embodiment of thepresent invention, and in which like numerals refer to vand even metalconstruction are such as to be liable to like parts throughout theseveral different views;

Fig. 1 is a face view of a propeller.

Fig. 2 is a longitudinal sectional view taken centrally of thepropellershown in Fig. l. v

Fig. 3 is an enlarged sectional ,view taken on the line 3-3 of Fig. l.

Fig. 4 is an enlarged sectional view taken on the line 4 4 of Fig 1.

Fig. 5 is an enlarged section of a fragment of one of the blades showingthe same case hardened.

One of the greatest problems in connection with airplane propellers isthe designing of the same to withstand the stresses set up in them athigh rotational speeds, due to the centrifugal forces acting at suchspeeds. It is generally necessary 1n connection with the present dayairplane practice where high l l speed internal combustlon engines areein-- ployed as a driving element, to provide a reduction device of onetype or another between the propeller and the engine. This has beennecessitated not so much by the possibility of less efficient reactionof the propeller on the air at high rotational speeds, as it is by thelimitation of the strength in existing propellers. Even with theseconventional reduction gears it is not. a relatively uncommon occurrenceto have a propeller damaged when the airplane goes into a nose-dive, atwhich time the propeller may be driven at a speed as high at greaterthan the normal maximum speed imparted thereto by the engine, and thedamage in such cases is usually found vto be due to the largecentrifugal forces set up in the propeller by. the high rotationalspeeds. In this connection, it is generally accepted that direct drivenpropel- 1ers rotating at relatively high engine speeds would be verydesirable in case they could be produced to withstand the highrotational speeds to which they would be subjected, and yet would not beobjectionablebecause of being of abnormal weight. Propellers constructedof wood or of a com- 1 position of wood and metal are subjected torelatively rapid wear in rain or hail storms,

propellers of the lconventional all destruction due to bullets frommachine guns, rifles, and the like.

The principal object of the present invention is to provide a propellerwhich will eliminate to a great extent if not entirely, the 0bjectionsto the conventional types of propellers as above pointed out.

In order to provide a construction that will amply resist highcentrifugal forces without being excessively heavy, I prefer to form itas illustrated in the accompanying drawings in which I show a propellerof the conventional two blade type. The propeller is formed of two mainparts 11 and 12 each of which represents one half of the propeller, andeach half comprises one surface, of each of the blades together with aportion of the connecting hub. These halves 11 and 12 are preferablyformed of chrome vanadium steel having a chronium content of .8O to1.10, a vanadium content of .15 to .18 and a carbon content of .3() to.40 This gives an extremely tough structure. The halves 1()J and 11extend from the leading edge to the trailing edge of each of the bladesand from one end of the propeller to the other, and are forged, rolled,or otherwise formed from minimum thickness at the tips of the blades tomaximum thickness in the neighborhood of the hub, and each are formed tothe shape of the finished surfaces of the blades which they are toconstitute so that when they are secured together with theircorresponding edges in alignment, as will hereinafter be described, ahollow structure of great strength radially and axially of the propellerwill result. I prefer to secure these two halves 11 and 12 together bywelding with a chrome vanadium wire of the same composition as that ofthe metal of the blades themselves, and to perform the welding operationunder conditions which preclude oxidation (as by the so-callec atomichydrogen process in which all oxygen 1s eliminated from contact with theparts being welded during the welding operation, and which thereforeinsures a clean weld of maximum strength.

The two halves 11 and 12 are provided with openings such as 13 in theirrespective hub portions through which a tube such as 14 is threaded andin which the tube is suitably secured by a Weldingl operation such asthat above described. and other openings such as 15 may be provided forthe purpose of receiving bolts or the like for securing the hub to thedriving plane, or for other purposes. After the propeller is thusbuiltup, the welded portions are suit-ably trimmed and the exteriorsurface of the propelleris in general finished and preferably polished.

Although it may not be necessary in all cases, I then prefer to caseharden the surface of the propeller so as to increase the strength andstiffness of thestructure, as well as to make it more impervious tomachine gun or rifle bullets, as well as to the natural elements. Thepreferred type of steel referred to above is, in and of itself,non-hardening, that is, it does not have suthcient carbon content to becapable of producing what is known as a hard surface upon heating andquenching but requires a carbonizing operation, in order to produce sucha hard surface. This may be accomplished bythe ordinary method ofpacking it in bone, subjecting it to the usual heating, and thenquenching it, but I prefer to carbonize it by heating it ina gas fiamesuch as butane, or other carbonizlng for a suitable length of time andthereafter quenching it, as by this method a quicker and equallyeflicient case may be obtained. This case is illustrated in, Fig. 5. Thepropeller may now again be polished, and is ready for use.

It will be apparent that the propeller manufactured as above describedwill be of maximum strength and rigidity, will be capable ofwithstanding extremely high rotational speeds without undulystressingthe same, will resist the action of the elements because of the natureof the material from which it is made and the manner in which it issecured together, and if casehardened as described, will be relativelyresistive to the effects of bullets and the like.

It will also be apparent that although I have described a particularmethod of making an entire propeller which is case hardened as a Whole,that a propeller may be built up of separate blades, each of which isany suitable construction and case hardened before assemblying, withoutmaterially departing from this particular phase of the presentinvention.

Formal changes may be made in the specic embodiment of the inventiondescribed without departing from the Aspirit or substance of the broadinvention, the scope of which is commensurate with the appended claims.

What I claim is:

1. An airplane propeller of the two-blade type formed of two halvesleach extending the full length of said propeller, one of said halvesserving to form the front face of both blades and the other of saidhalves serving to form the rear face of both blades, said halves beingjoined to each other by welding along the leading and trailing edges ofsaid blades, the metal of each of said halves gradually increasing inthickness from the tips of said blades and adjacent the hub of saidpropeller.

2. An airplane propeller formed of two halves joined together alonglines extending lengthwise of said propeller to form a hol'- lowstructure, said halves being formed of non-hardenin casehardenefsurface.

4. A steel hollow propeller blade having its outer surface hardened to adepth -constituting a material proportion of the average thickness ofthe walls of said blade.

4 5. A hollow propeller blade formed of tough steel and having wallswhich outwardly iminish in thickness and which are provided with ahardened outer surface of sufficient thickness to impart a desiredrigidity thereto. 'v

6. An airplane propeller having integrally connected hollow steel bladesexteriorly case hardened.

7 The method of building an airplane propeller comprising: forging twosteel halves, each of said halves representing one surface of saidpropeller from one end thereof to the other end thereof and increasingin thickness from the ends to adjacent the center, welding to unite saidedges, placing said halves together withcontacting edges, and theraftercarbonizing the surface of the welded struc-- ture, and then quenchingsaid structure.

8. The method of making an airplane propeller comprising: first formingtwol steel halves each representing one surface o'f said propeller from'end to end and each increasing in thickness from theen'ds towards thecenter,'placing said halves in superposed'position with theircorresponding edges in matching relationship, welding said edges to-Oether under conditions which preclude oxi- 'datio-n, subjecting saidwelded halves, as thus united, externally to the action of a heating gasoverrich in carbon until the surfaces of said halves have absorbed aypredetermined amount of carbon, and then quenching said halves toharden said surfaces. L

9. A propeller blade formed generally of non-hardemng steel and having acase hardened surface.

JOHN sQmREs.

steel and having a complete A.

